Date of Award

5-2013

Level of Access

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Ecology and Environmental Sciences

Advisor

Francis A. Drummond

Second Committee Member

Malcolm Hunter

Third Committee Member

William E. Glanz

Abstract

Beneficial arthropods, including native bees, predators, and parasitoids, provide valuable ecosystem services, which help to maintain agricultural productivity and reduce the need for pesticide inputs. This thesis synthesizes research regarding arthropod- mediated ecosystem services from a number of prominent Vaccinium agroecosystems worldwide as well as provides novel research regarding predator and scavenger mediated ecosystem services in the Maine wild blueberry agroecosystem. It is my hope that researchers and growers might be able to utilize research methods, results, and conservation recommendations provided within this document.

Predators and scavengers can play a vital role in regulating pest insect and weed populations and are especially important to organic agricultural production. In addition to pest and weed suppression, some arthropods have the ability to degrade vertebrate feces at high rates. In response to recent foodborne pathogen outbreaks, it is becoming increasingly important to examine the role of coprophagous insects in the agricultural arena. During the years 2011 and 2012, these ecosystem services provided within both the lowbush blueberry (Vaccinium angustifolium) agroecosystem and surrounding landscape were examined. The objective of this study was to quantify how differential field management and surrounding forest composition interact to drive insect predator and scavenger mediated ecosystem services. Additionally, pitfall trapping and time-lapse, macro-video footage were used to better understand the composition of the arthropod community providing these services.

Significantly greater amounts of predation and scavenging occur within field interiors than at field edges and adjacent forests thought the pattern of these interactions varies between repetitions. While arthropods were found to be the main predators and scavengers, vertebrates were shown to play a significant role in resource removal under certain treatment combinations. Arthropod predators were unevenly distributed with regards to the field/forest edge. The main insect predators likely accounting for these patterns in predation/scavenging are ants (Hymenoptera: Formicidae), crickets (Orthoptera: Gryllidae), ground beetles (Coleoptera: Carabidae), and dung beetle (Coleoptera: Scarabaeidae).

Wildlife as a source of microbial contamination is a concern among public health and food safety agencies. We used the lowbush blueberry agroecosystem as a model system in which to test multiple, broadly applicable, food safety questions. In a lab study, the ecological role of the dung beetle species, Onthophagus hecate, was explored as a potential natural biological control agent of feces-borne pathogens, and alternatively as a pathogen vector between feces and food. We conducted a laboratory study to elucidate aspects of dung beetle feeding ecology as they relate to suppression and/or transmission of E. coli 0157:H7 from white tailed deer feces to pre-harvest lowbush blueberry fruit.

Results indicate that beetles buried the same percentage of feces whether or not it was inoculated with the pathogen (F(1,6)< 0.001; P=0.99). Beetles were found to vector no detectable amount of the pathogen to the fruit. Lastly, dung beetles lowered the amount of pathogenic E. coli persisting in the soil (F(2,9)= 7.75; P = 0.01). Therefore, our study suggests that the generalist dung beetle species, Onthophagus hecate, when present in agroecosystems, has the potential to suppress E. coli 0157:H7.

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